When he returned to manage Chelsea, it seemed that José Mourinho had decided to play the game of a controlled manager and not to repeat the extravagant behaviour that he often exhibited in his first spell at the club.

I remember, for instance, him running up and down the touchline shouting at the referee, waving a laptop in his hand on which he had obviously been watching the match televised live.

He believed that a replay had shown that a vital decision made by the referee had been incorrect. His newly found calm vanished, however, at the Premier League match with Manchester City when he jumped up and down waving his arms in the air after a Chelsea player was fouled.

His ranting was at the referee’s decision not to send off the City player for what Mourinho considered was an ‘obvious goal-scoring opportunity’.

There is no doubt that the City player brought down the Chelsea forward and that he was, what many people think is a criteria, the last defender before the goalkeeper.

The offence took place inside the centre circle, so how realistic was his claim?

This law was introduced in 1997 to try to prevent, or curtail, what was called the ‘professional’ foul.

I always thought that was an odd description.

Surely to be a member of a profession should be something to be proud of and yet here it is being used to describe underhand behaviour.

Sadly of course, as so often is the case, it comes down to, if not the instructions of the coaches, then at least their approval.

I remember the revered Bobby Charlton when commenting on television about a goal that was scored, saying the manager would have been disappointed that his defender hadn’t brought the player down to prevent his shot on goal.

This to me showed how much this tactic had become ingrained in professional football.

Let us look at what the law actually says.

‘A player is sent off if he denies an obvious goalscoring opportunity, to an opponent moving towards the player’s goal, by an offence punishable by a free kick or penalty kick.’

The first thing is to consider is what does it mean by obvious.

We are looking at something that is almost inevitable; scoring is a probability not a possibility.

There are, however, five circumstances laid down in the guidelines to referees in the Laws of the Game, which a referee must take into consideration.

One of these is that there must be a foul committed that is punishable by a direct or indirect free kick.

So even impeding, an indirect offence, would warrant a sending off.

Then there is the number and location of other defenders.

This means that even if the offender is the last defender, it would not be an obvious goalscoring opportunity if there were other defenders who could easily retreat to thwart the attacker.

Next is the direction of play.

The law requires that the attacker must be moving towards the opponent’s goal.

Often you see players being brought down in the penalty area when they are not heading towards the goal, which would have made scoring more difficult.

The referee also has to be certain that the player had control of the ball or could have regained control had he not been brought down.

Then, say the guidelines, the referee must take into consideration the distance between the offence and the goal.

Obviously, the further away from goal, the more things that could go wrong, so reducing the chance of scoring.

Did José Mourinho really think that a foul committed so far away from goal, qualified as denying an obvious goalscoring opportunity?